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astro_al

Driven Mount for a 120mm Refractor

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I currently have a 120mm refractor mounted on a Giro Ercole and a Berlebach UNI tripod. At higher magnifications I am getting a bit too much shaking when focussing, and having to frequently nudge the mount along is more distracting than I hoped it would be. The same sort of alt-az setup is perfect for my smaller refractor, but I am thinking about swapping out the larger set-up for a driven mount. 

Not too bothered about Goto, won’t be doing any astrophotography, and will have a maximum load of 10KG. Ideally should have or should support an upgrade to a Losmandy saddle. I was thinking about a Losmandy GM-8 with the digital drive option (top end of my budget), I also keep coming back to the Skywatcher AZ EQ5-GT as I like alt-az style observing plus it is cheaper and I keep telling myself that for visual observing I don’t need to go overboard on the mount i.e. keep some astro funds for new binoviewers or another scope. 

I have read a few negative comments on SGL about the GM-8, but that could be from an astrophotography perspective - not sure. Anyway, I would appreciate any input for those of you with either a GM-8 or an AZ EQ5-GT or if you have a 120mm ish refractor mounted on something else that you think is a good fit. @F15Rules already suggested a Takahashi EM-2 which looks awesome, but I think I would be lucky to find a non-goto Tak Mount like an EM-2 or EM-10. Although you never know what a wanted add might turn up!

Thanks for your help.

Al

Edited by astro_al

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Hi again Al,

Agree the Tak non gotos are rare in the UK.

How about the beefed up Vixen GP DX? The Vixen GPs are superbly engineered and the DX is, I believe, rated at 10kg payload.

Dweller25 on this site has his FS128 on one I think..

HTH,

Dave

 

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A second hand EQ6 goto would fit the bill- you should pick one up for around £600 used. Plenty of capacity for a 120mm refractror and more. Don't rule out goto mounts- in my experience they save so much time finding targets!

Edited by laser_jock99

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I use an AZ-EQ 6 with my 125mm (f9) achro, mostly for visual. I think it supports up to around 18kg for imaging and c. 25kg for visual. Will take vixen and losmandy. Very robust and steady.  Bit pricier than an AZ-eq 5, but way cheaper than a GM :).

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6 minutes ago, F15Rules said:

How about the beefed up Vixen GP DX? The Vixen GPs are superbly engineered and the DX is, I believe, rated at 10kg payload.

I have been looking at the GPDX as there is one on UKABS at the moment. I would be right at the limit of its load capacity though. 

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7 minutes ago, laser_jock99 said:

A second hand EQ6 goto would fit the bill- you should pick one up for around £600 used. Plenty of capacity for a 120mm refractror and more. Don't rule goto mounts- in my experience they save so much time finding targets!

Thanks. Definitely wouldn’t rule out a mount that has Goto, it is just not a requirement. I have read a lot of good things about the EQ6. 

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6 minutes ago, Marki said:

I use an AZ-EQ 6 with my 125mm (f9) achro, mostly for visual. I think it supports up to around 18kg for imaging and c. 25kg for visual. Will take vixen and losmandy. Very robust and steady.  Bit pricier than an AZ-eq 5, but way cheaper than a GM :).

The AZ-EQ 6 is getting close to the GM-8 (non GoTo) in price and is possibly a bit too heavy for me. It does look good though. 

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My 120 Equinox is happy enough for visual on my driven EQ5.

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11 minutes ago, laser_jock99 said:

A second hand EQ6 goto would fit the bill- you should pick one up for around £600 used. Plenty of capacity for a 120mm refractror and more. Don't rule out goto mounts- in my experience they save so much time finding targets!

Good suggestion. Steve Bennett (Saganite on SGL) has my ex scope on the older, black EQ6 non-goto version.. the scope is  5" D&G F15 achromat fully 2m long, with Moonlite 2" focuser, and weighing around 12-14 kg depending on finder and eyepieces.

I have seen these older ones now and again used for c£300.

Dave

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15 minutes ago, astro_al said:

I have been looking at the GPDX as there is one on UKABS at the moment. I would be right at the limit of its load capacity though. 

In my experience both Tak and Vixen mounts are conservatively rated, and over-engineered versus their stated tolerances?.

Dave

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14 minutes ago, astro_al said:

The AZ-EQ 6 is getting close to the GM-8 (non GoTo) in price and is possibly a bit too heavy for me. It does look good though. 

Ah yes - should have looked at the non go-to; not too far off in price although the Az-eq does come with legs. The mount is indeed quite heavy though - I tend to leave mine set up, rather than break ir down after each session for that very reason. Good luck with your choice though :).

 

Edited by Marki
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12 minutes ago, astro_al said:

I have been looking at the GPDX as there is one on UKABS at the moment. I would be right at the limit of its load capacity though. 

I suspect that on a decent tripod, a GP-DX would be a pretty good option. The rating on the Japanese mounts is quite conservative. I had a C925 on a Vixen GP and it coped very well for visual. EQ6 Goto might be easier to find and will do the job well.

I find high power planetary and lunar observing with a simple tracking EQ mount very good, much more relaxing and I see more than when nudging a manual Alt-Az mount.

When I'm star hopping though, an alt-az mount seems far more intutitive and I guess it is generally at low to mid power so nudging to follow the target is less frequent and vibrations less intrusive.

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A Celestron CG5 would do the job but it's not as nicely finished as the Vixens of course. I use an older non-GOTO HEQ5 for my TMB/LZOS 130 F/9.2 triplet and that scope is a lot more challenging for a mount than the Tak TSA120 is.

The more up to date Celestron AVX also did a decent job on the TMB/LZOS. I don't have use for GOTO either but it's easy to skip straight to tracking and bypass the GOTO setup with the AVX.

 

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1 minute ago, astro_al said:

Thanks @Stu and @F15Rules. Sounds like the GPDX is worth investigating further. 

Al

Particularly given Moonshane's comments regarding his Equinox on an EQ5, the GPDX is a substantial step up from that.

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1 hour ago, Stu said:

Particularly given Moonshane's comments regarding his Equinox on an EQ5, the GPDX is a substantial step up from that.

Yep, the GPDX Vs standard EQ5 is "men Vs boys"??..

Dave

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After a short detour on my way back from Yorkshire I now have a GPDX! Less than two days since it was suggested, funny how things sometimes work out ?. Pictured with my smaller scope which I will start with for the first few sessions until I know what I am doing (it’s been at least 10 years since I used a Goto mount). For the larger scope I may put the DX on my UNI tripod and fit the Losmandy saddle from my Ercole - makes it so much easier to get the scope on and off. Hopefully I can get an ADM puck that will play nicely. 

Thanks to everyone who posted.

Al

BE89B8DC-994C-4103-968D-76B8F2DC19F5.jpeg

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It turns out that I can use my existing counterweights, and that I can fix the DX to my UNI mount by swapping the 3/8” bolt for a longer M10 bolt and using the head of the original tripod ?. 

Just need to sort out a puck for my Losmandy saddle and I will be all set. 

967F534A-3815-4CA1-B4D2-408B54501A1A.jpeg

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Hi Franck,

That is a really nice looking setup. Unfortunately a 10 Micron Mount is well outside of my budget. Maybe something for the future. 

Al

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